The 46-year-old computer expert from Amsterdam went hiking in Norway last month. He was set to return to the Netherlands on August 22nd, but never made it back. His employer reported him missing on August 29th, according to the police. He was last seen in Bodø on August 20th.

On August 30th, his phone was turned on in the vicinity of Vikeså, around 50 kilometers south of Stavanger. The phone was turned on for 20 minutes. After that, the SIM card was removed and a German SIM card was put into the phone. The Norwegian police is currently trying to track the history of that SIM card.

On Monday a witness reported seeing Kamphuis in Denmark, according to the police. A search for him was therefore also launched there.

On Wednesday, September 5th, the Dutch police received information that Kamphuis bought a folding kayak in the Netherlands for his vacation. According to the seller, he planned to go kayaking at the fjords in Norway. This information was shared with the Norwegian authorities.

Earlier this week the Norwegian police called in special unit Kripos to help in the search for Kamphuis, according to RTL Nieuws. The unit investigates organized crime and is often used in missing person cases.

Kamphuis is an expert in online security and previously warned about the dangers of cyber espionage and vulnerabilities in the Netherlands' election software. He worked with various whistleblowers in the past and also worked with WikiLeaks. He personally knows WikiLeaks founder Julian Assange. The police do not currently think that his disappearance is linked to his work, according to the broadcaster.